original_kernel/arch/sh/mm/pg-sh4.c

/*
 * arch/sh/mm/pg-sh4.c
 *
 * Copyright (C) 1999, 2000, 2002  Niibe Yutaka
 * Copyright (C) 2002 - 2007  Paul Mundt
 *
 * Released under the terms of the GNU GPL v2.0.
 */
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/fs.h>
#include <asm/mmu_context.h>
#include <asm/cacheflush.h>

#define CACHE_ALIAS (current_cpu_data.dcache.alias_mask)

static inline void *kmap_coherent(struct page *page, unsigned long addr)
{
	enum fixed_addresses idx;
	unsigned long vaddr, flags;
	pte_t pte;

	inc_preempt_count();

	idx = (addr & current_cpu_data.dcache.alias_mask) >> PAGE_SHIFT;
	vaddr = __fix_to_virt(FIX_CMAP_END - idx);
	pte = mk_pte(page, PAGE_KERNEL);

	local_irq_save(flags);
	flush_tlb_one(get_asid(), vaddr);
	local_irq_restore(flags);

	update_mmu_cache(NULL, vaddr, pte);

	return (void *)vaddr;
}

static inline void kunmap_coherent(struct page *page)
{
	dec_preempt_count();
	preempt_check_resched();
}

/*
 * clear_user_page
 * @to: P1 address
 * @address: U0 address to be mapped
 * @page: page (virt_to_page(to))
 */
void clear_user_page(void *to, unsigned long address, struct page *page)
{
	__set_bit(PG_mapped, &page->flags);
	if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
		clear_page(to);
	else {
		void *vto = kmap_coherent(page, address);
		__clear_user_page(vto, to);
		kunmap_coherent(vto);
	}
}

/*
 * copy_user_page
 * @to: P1 address
 * @from: P1 address
 * @address: U0 address to be mapped
 * @page: page (virt_to_page(to))
 */
void copy_user_page(void *to, void *from, unsigned long address,
		    struct page *page)
{
	__set_bit(PG_mapped, &page->flags);
	if (((address ^ (unsigned long)to) & CACHE_ALIAS) == 0)
		copy_page(to, from);
	else {
		void *vfrom = kmap_coherent(page, address);
		__copy_user_page(vfrom, from, to);
		kunmap_coherent(vfrom);
	}
}

/*
 * For SH-4, we have our own implementation for ptep_get_and_clear
 */
inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
{
	pte_t pte = *ptep;

	pte_clear(mm, addr, ptep);
	if (!pte_not_present(pte)) {
		unsigned long pfn = pte_pfn(pte);
		if (pfn_valid(pfn)) {
			struct page *page = pfn_to_page(pfn);
			struct address_space *mapping = page_mapping(page);
			if (!mapping || !mapping_writably_mapped(mapping))
				__clear_bit(PG_mapped, &page->flags);
		}
	}
	return pte;
}